Silicon materials, such as silicon (Si) and silicon oxide represented by SiOx, are known to intercalate more lithium ions per unit volume than carbon-based materials, such as graphite. For example, Patent Literature 1 and Patent Literature 2 disclose non-aqueous electrolyte secondary batteries that have a negative electrode containing a silicon-based active material and in which polyacrylic acid is used as a binder in the negative electrode mixture layer. Since silicon materials undergo a larger volume change associated with charging and discharging than graphite, the combined use of graphite and a silicon-based active material has been proposed in order to improve the capacity of batteries and maintain a favorable cycle life.